Script reissue vs. EVH Phase 90 : what changes?

All about modern commercial stompbox circuits from Electro Harmonix over MXR, Boss and Ibanez into the nineties.
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kymar
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Post by kymar »

Dunlop EVH phase 90 schematic need or tell me resistors value marked on PCB EVH Phase 90 as R5 & R6. please!

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lolbou
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Post by lolbou »

Hi.

Say "Hi" too, and post in the appropriate section (Requests) please.

Also perform a search before posting. viewtopic.php?f=1&t=3893&hilit=evh+phase might bring you some info...
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Post by Dirk_Hendrik »

kymar wrote:Dunlop EVH phase 90 schematic need or tell me resistors value marked on PCB EVH Phase 90 as R5 & R6. please!
buy one, trace it, post the schem here..

dammit.. I almost start to agree with Puretube on his "schemmo's for nothing..." theme :roll:
Sorry. Plain out of planes.

http://www.dirk-hendrik.com

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kymar
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Post by kymar »

Ok, guys. I have one, but csp-101 not evh. I want to modify it to evh, because it has the same pcb (smd version) only missing resistors R5 & R6 (R28 mod). I guess they are both R28 (1/2 R28 each) or only one of them is R28. i cant accurace trace it because there are many big details on pcb. I ask owners of evh phase to tell me values of this resistors. or if somebody have shcematic for it.....

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Post by lolbou »

Can't you get the missing values from the topic I linked above? These are supposed to be identical, except for a switch (I read it fastly, it may be more complicated...)...

Can you post your references for this R28 mod you quote (link?)?
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kymar
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Post by kymar »

New dunlop phase 90 script edition CSP-101s/sl made on one pcb as EVH phase 90 (Rev.B). It (CSP ed) has switch button on pcb which doesnt work and there are two missing resistors marked R5 & R6 (numbers not the same as in older schematic). This push button switch between Script and Block mods in EVH version, on/off R28 mod i guess. In script version (CSP) new Block mod switch off, it meens there no R28 resistor and maybe another mods (such as R9 (R22 in old schema) is 4M7) but there are no empty places on pcb. So R5 & R6 resistors must be R28 mod and have values 10-12K. But i am not sure, because cant trace it accurace. And i dont know why R28 divided into two R5 & R6. I cant check my guesses in practice bacause havent have smd components to solder.

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kymar
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Post by kymar »

I trace this problem. R5 & R6 are both R28 mod resistors stay in parallel and be connected one or another by SPDT switch between second phase stage and R34 & 7 pin of IC2. It means one of them is 20-24k but another???? What for it is necessary???

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Post by Bside2234 »

R6 is empty and R5 is 243

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Post by guiddruid »

A common reason to use more than one resistor, in a low-power circuit, is to obtain a value not otherwise available in a standard E24/whatever series. Very common in adjustable voltage regulator circuits. My guess would be that the resistor in EVH's original pedal is a trimmer, which was adjusted to sound right. Two resistors were allowed for on the PCB so the value could be closer to the original. Presumably it was then decided that the difference in sound wasn't worth the extra 0.5c.

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kymar
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Post by kymar »

Thank you Bside2234!
This is Dunlop marketing to sold one same pedal as three different. New dunlop 90 phasers (except 74 reissue) are made on one double side smd pcb, marked as EVH phase 90 Rev.B. Numbers of components on this pcb not the same as in older versions. R5 & R6 on this pcb are both "R28 mod" resistors stay in parallel and be connected one or another by SPDT switch (real DPDT switch but one side dont work) between second phase stage and R34 & 7 pin of U1(IC2). This push button on pcb works as switch between Script and Block mods in EVH version (on/off R28 mod). In Script phase version Block mod constantly switch off, it meens there no R28 resistor at all (R5 & R6 is empty places and push button switch doesnt work). In Block phase version Script mod constantly off, it means R5&R6 have the same values (R28 resistor is allways on, push switch again doesnt work). And in EVH phase version R5 is on place and R6 is absent, so the push button works switching on/off R28 mod. I have custom shop phase 90 CSP-101s and R5 & R6 where absent. I solder 0,25W 24K smd resistor on R5 place and make my phase to be EVH phase version with switchable R28 mod. Thanks Dunlop to leave push button on place, otherwise It would be necessary to solder it :D . So dont waste your money!

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Post by lolbou »

Good to see it sorted out and explained! I change the topic title and place it in the now more appropriate section.

Thanks fellas!
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